1. Field
The inventive concept relates to an interference cancellation relay device, and particularly, to an interference cancellation relay device having a pre-distortion function.
2. Description of Related Art
In general, a relay device is used for transmitting a signal between a base station and a terminal and extension of a service or improvement of a service quality in a radio signal shadow area. A wireless relay device may be provided as one example of the relay device, and the wireless relay device provides a communication service for receiving the signal transmitted from the base station or the terminal through a receiving antenna, amplifying the received signal, and transmitting the amplified signal to the terminal or the base station through a transmitting antenna.
In the case of the wireless relay device, a degree of isolation at a predetermined level or higher is required between the receiving antenna and the transmitting antenna in order to prevent deterioration in quality of the communication service. In recent years, as it has been difficult to secure the degree of isolation due to a spatial limitation according to a miniaturization demand trend of the wireless relay device, a research into an interference cancellation relay device has been actively conducted, which can secure the degree of isolation while overcoming the spatial limitation by applying an interference cancellation function to cancel feed-back signals, that is, signals input into the receiving antenna as interference signals through a variety of paths, after the signals are radiated from the transmitting antenna.
In addition, the radio relay device has a power amplifier at a transmitting end to transmit a signal having sufficient power to the terminal or the base station and the deterioration in quality of the communication service is caused due to a non-linear characteristic of the power amplifier. For preventing the quality deterioration, an attempt for implementing a pre-distortion function for improving the non-linear characteristic of the power amplifier in the wireless relay device has been continued and in particular, an attempt for implementing the pre-distortion function even in the interference cancellation relay device has been actively made.
However, in the case of the interference cancellation relay device, since the received signal significantly fluctuates due to the interference signals, it is difficult to implement the pre-distortion function therein.